Altered antioxidant and trace-element status in adolescent female gymnasts

Physical activity is associated with the generation of reactive oxygen species and may lead to decreased levels of plasma antioxidants and increased oxidant stress. Some studies have reported that antioxidant supplements can reduce the consequences of oxidative stress during exercise. In this study the authors aimed to assess the chronic effects of exercise on endogenous serum antioxidant enzyme concentrations. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity were measured in adolescent girls who were either competitive gymnasts or sedentary controls. The relationship between age, body-mass index, dietary intake, trace-element status, and serum GPx and SOD was determined. The participants in the study were part of a 3-yr longitudinal investigation of exercise and peak bone-mass development in 38 competitive gymnasts and 40 healthy sedentary adolescent females 8-17 yr of age. Serum GPx and SOD were measured using colorimetric assays, and trace elements were measured using inductively coupled plasma mass spectrometry. The mean serum GPx concentrations were significantly higher in the gymnasts than in the sedentary females (157 ± 11.1 vs. 126 ± 8.8 U/ml, p < .05). In contrast, serum SOD concentrations were significantly lower in the gymnasts than in the sedentary group (7.24 ± 2.6 vs. 8.57 ± 2.3 U/ml, p < .05). Serum selenium, zinc, and copper were higher in the physically active group than in the inactive group (0.89 ± 0.03, 10.86 ± 0.39, 14.50 ± 0.50 vs. 0.81 ± 0.03, 10.32 ± 0.28, and 14.38 ± 0.42 µmol/L, respectively), although only serum selenium reached statistical significance (p < .05). The findings show that young female gymnasts have an altered antioxidant enzyme profile compared with their less physically active peer

Is there a role for vitamin C in preventing osteoporosis and fractures?:A review of the potential underlying mechanisms and current epidemiological evidence

Osteoporosis and related fractures are a major global health issue, but there are few preventative strategies. Previously reported associations between higher intakes of fruits and vegetables and skeletal health have been suggested to be partly attributable to vitamin C. To date, there is some evidence for a potential role of vitamin C in osteoporosis and fracture prevention but an overall consensus of published studies has not yet been drawn. The present review aims to provide a summary of the proposed underlying mechanisms of vitamin C on bone and reviews the current evidence in the literature, examining a potential link between vitamin C intake and status with osteoporosis and fractures. The Bradford Hill criteria were used to assess reported associations. Recent animal studies have provided insights into the involvement of vitamin C in osteoclastogenesis and osteoblastogenesis, and its role as a mediator of bone matrix deposition, affecting both the quantity and quality of bone collagen. Observational studies have provided some evidence for this in the general population, showing positive associations between dietary vitamin C intake and supplements and higher bone mineral density or reduced fracture risk. However, previous intervention studies were not sufficiently well designed to evaluate these associations. Epidemiological data are particularly limited for vitamin C status and for fracture risk and good-quality randomised controlled trials are needed to confirm previous epidemiological findings. The present review also highlights that associations between vitamin C and bone health may be non-linear and further research is needed to ascertain optimal intakes for osteoporosis and fracture prevention

Postgraduate Symposium Positive influence of nutritional alkalinity on bone health: Conference on ‘Over- and undernutrition: challenges and approaches'

There is growing evidence that consumption of a Western diet is a risk factor for osteoporosis through excess acid supply, while fruits and vegetables balance the excess acidity, mostly by providing K-rich bicarbonate-rich foods. Western diets consumed by adults generate approximately 50-100 mEq acid/d; therefore, healthy adults consuming such a diet are at risk of chronic low-grade metabolic acidosis, which worsens with age as a result of declining kidney function. Bone buffers the excess acid by delivering cations and it is considered that with time an overstimulation of this process will lead to the dissolution of the bone mineral content and hence to reduced bone mass. Intakes of K, Mg and fruit and vegetables have been associated with a higher alkaline status and a subsequent beneficial effect on bone health. In healthy male volunteers an acid-forming diet increases urinary Ca excretion by 74% and urinary C-terminal telopeptide of type I collagen (C-telopeptide) excretion by 19% when compared with an alkali (base-forming) diet. Cross-sectional studies have shown that there is a correlation between the nutritional acid load and bone health measured by bone ultrasound or dual-energy X-ray absorptiometry. Few studies have been undertaken in very elderly women (>75 years), whose osteoporosis risk is very pertinent. The EVAluation of Nutrients Intakes and Bone Ultra Sound Study has developed and validated (n 51) an FFQ for use in a very elderly Swiss population (mean age 80·4 (sd 2·99) years), which has shown intakes of key nutrients (energy, fat, carbohydrate, Ca, Mg, vitamin C, D and E) to be low in 401 subjects. A subsequent study to assess net endogenous acid production (NEAP) and bone ultrasound results in 256 women aged ≥75 years has shown that lower NEAP (P=0·023) and higher K intake (P=0·033) are correlated with higher bone ultrasound results. High acid load may be an important additional risk factor that may be particularly relevant in very elderly patients with an already-high fracture risk. The latter study adds to knowledge by confirming a positive link between dietary alkalinity and bone health indices in the very elderly. In a further study to complement these findings it has also been shown in a group of thirty young women that in Ca sufficiency an acid Ca-rich water has no effect on bone resorption, while an alkaline bicarbonate-rich water leads to a decrease in both serum parathyroid hormone and serum C-telopeptide. Further investigations need to be undertaken to study whether these positive effects on bone loss are maintained over long-term treatment. Mineral-water consumption could be an easy and inexpensive way of helping to prevent osteoporosis and could be of major interest for long-term prevention of bone los

Very high prevalence of 25-hydroxyvitamin D deficiency in 6433 UK South Asian adults : Analysis of the UK Biobank Cohort

Acknowledgements This research has been conducted using the UK Biobank Resource under application number 15168. This work was supported by in-house funds from the University of Surrey for payment of the UK Biobank access fee. The UK Biobank was established by the Wellcome Trust medical charity, Medical Research Council, Department of Health, Scottish Government and the Northwest Regional Development Agency. It has also had funding from the Welsh Assembly Government and the British Heart Foundation. UK Biobank is hosted by the University of Manchester and supported by the National Health Service (NHS). All the above funders had no role in the design, analysis or writing of the present study. Author contributions were as follows: Formulating the research question(s) (A. L. D., D. J. B., K. R. A., S. L. N.), designing the study (A. L. D., D. J. B., K. R. A., S. A. L.-N.), data collection (not applicable), analysing the data (A. L. D., D. J. B., K. R. A., S. A. L.-N.) and writing the article (A. L. D., D. J. B., K. R. A., S. L. N.). S. A. L.-N. discloses that she is Research Director of D3-TEX limited which holds the UK and Gulf Corporation Council (GCC) patents for the use of UVB transparent clothing to prevent vitamin D deficiency. S. A. L.-N.’s husband William Lanham-New is Managing Director of D3-TEX limited. S. A. L.-N. has received grants from (1) The UK Biotechnology and Biological Sciences Research Council (BBSRC) (project: Ergocalciferol (D2) v. Cholecalciferol (D3) Food Fortification: Comparative Efficiency in Raising 25OHD Status & Mechanisms of Action (D2–D3 Study), BB/I006192/1, £516 823); (2) The UK Food Standards Agency (Project: Vitamin D, Food Intake, Nutrition and Exposure to Sunlight in Southern England (D-FINES) Study, N05064, £600 000); (3) The European Union (Project: Food Based Solutions for optimal vitamin D nutrition and health through the life cycle, Lead Work Package; (4) nutritional requirements for vitamin D during pregnancy, childhood and adolescence using RCTs, FP7-613977-ODIN, Euro 6·2 million) and (5) The UK Ministry of Defence (MoD, £2·4 million). S. L. N. is a current member of the Scientific Advisory Committee for Nutrition (SACN) and a member of the panel who was responsible for the most recent revision of vitamin D recommended nutritional intake guidelines in the UK. She is a board member for the UK Royal Osteoporosis Society and the British Nutrition Foundation. She is Secretary of the Nutrition Society as well as Editor in Chief of the Nutrition Society textbook series. All other authors have no conflict of interest.Peer reviewedPublisher PD